1. Field of the Invention
The present invention relates to an image reading device. More particularly, the present invention relates to an image reading device for reading image information from photo film by use of CCD or the like.
2. Description Related to the Prior Art
There is a known image reading device, such as a scanner, which reads image information from developed photo film by use of CCD (charge coupled device), and processes the image information digitally. In combination with this, a printer is operated to record the image on to photographic paper or the like according to the image information. In the scanner, a light passing opening is formed in a photo film passageway. Light from a light source is passed through the light passing opening, and caused to illuminate the photo film. Light transmitted through the photo film is picked up by the CCD, by which the image information is read.
In addition to the image information, the CCD reads various bar codes and other information arranged on longitudinal edges of the photo film. It is noted that perforations are formed in the photo film and arranged at a regular pitch for the purpose of the photo film advance and positioning of a frame of an image. The perforations pass a position of the CCD in the course of the reading of the CCD for the image information, photo film type information or the like. In response to the passage of the perforations, the light passed through the perforations becomes an excessively high amount as a part of the light coming incident upon the CCD. Thus, it is necessary to lower the amount of the light at the perforations for avoiding saturation of an output of the CCD even with the light passed through the perforations. Japanese Patent Application No.09-276097 discloses a suggestion in connection with this problem. A light-passing glass plate is used, and is provided with an ND filter for reducing light in the position opposed to the perforations.
However, the prior art has a problem in that dust stuck on the photo film is likely to become stuck to the light-passing glass plate. The dust is read by the CCD clearly, to cause streak or noise in the image information being read.